Continuous Subcutaneous Insulin Infusion (CSII) may be the basis for therapy of insulin-dependent diabetes mellitus. In some examples of this therapy, a diabetic patient carries a miniaturized infusion pump quasi-continuously throughout night and day and possibly concealed from view. The infusion pump administers insulin via a cannula, the cannula being, e.g., made from medical-grade stainless steel or Teflon, into the subcutaneous fat tissue. The cannula may also be an arrangement of several cannulas such as a micro needle array, or the like.
According to a first administration regime, the insulin pump administers insulin in a continuous or quasi-continuous way as defined by patient-specific and time-of-day dependent basal profile in order to cover the patient's basal (i.e., meal-independent) insulin need. According to a second administration regime, the pump is adapted to administer comparatively large insulin boli on demand for covering the intake of food, namely carbohydrates, and to correct for undesirably high blood glucose values. Infusion devices which are adapted fort the CSII therapy of diabetes mellitus are disclosed, among others, in U.S. Pat. No. 6,878,132, which is incorporated by reference herein.
While quasi-continuous basal administration typically comprises small drug volumes, bolus volumes are considerably larger in some cases, often resulting in bad and delayed drug absorption and high internal tissue pressure, potentially resulting in tissue damage. In some cases, the insulin may, in total or in part, flow back from the cannula tip along the outer cannula surface and leave the body, resulting in a lack of drug administration.